Software Engineering

Hello, Name or World in Python

The challenge

Define a method hello that returns “Hello, Name!” to a given name, or says Hello, World! if name is not given (or passed as an empty String).

Assuming that name is a String and it checks for user typos to return a name with a first capital letter (Xxxx).


hello "john"   => "Hello, John!"
hello "aliCE"  => "Hello, Alice!"
hello          => "Hello, World!" <em># name not given</em>
hello ""       => "Hello, World!" <em># name is an empty String</em>

The solution in Python code

Option 1:

def hello(name=''):
    return f"Hello, {name.title() or 'World'}!"

Option 2:

def hello(name=''):
    return "Hello, {}!".format(name.title() if name else 'World')

Option 3:

def hello(name = ""):
    nameNow = ""
    if name == "":
        return "Hello, World!"
    j = 0
    for i in name:
        if j == 0:
            temp1 = i.upper()
            nameNow = nameNow + temp1
            j += 1
            temp1 = i.lower()
            nameNow = nameNow + temp1
    return "Hello, " + nameNow + "!"

Test cases to validate our solution

import test
from solution import hello

@test.describe("Fixed Tests")
def fixed_tests():'Basic Test Cases')
    def basic_test_cases():
        tests = (
            ("John", "Hello, John!"),
            ("aLIce", "Hello, Alice!"),
            ("", "Hello, World!"),
        for inp, exp in tests:
            test.assert_equals(hello(inp), exp)

        test.assert_equals(hello(), "Hello, World!")

@test.describe("Random Tests")
def random_tests():

    from random import randint, choice
    NAMES = [
        "James", "Christopher", "Ronald", "Mary", "Lisa", "Michelle",
        "John", "Daniel", "Anthony", "Patricia", "Nancy", "Laura",
        "Robert", "Paul", "Kevin", "Linda", "Karen", "Sarah", "Michael",
        "Mark", "Jason", "Barbara", "Betty", "Kimberly", "William", "Donald",
        "Jeff", "Elizabeth", "Helen", "Deborah", "David", "George", "Jennifer",
        "Sandra", "Richard", "Kenneth", "Maria", "Donna", "Charles", "Steven",
        "Susan", "Carol", "Joseph", "Edward", "Margaret", "Ruth", "Thomas",
        "Brian", "Dorothy", "Sharon", ""
    def create_test_case():
        return "".join(c.lower() if randint(0, 200) % 3 else c.upper() for c in choice(NAMES))
    reference = lambda n='', d='World': "Hello, %s!" % (n or d).title()
    for _ in range(100):
        test_case = create_test_case()"testing for hello({test_case})")
        def test_case():
            test.assert_equals(hello(test_case), reference(test_case))